Windows and the test runner

Right now we have the url dependency in xee-testrunner just to support running the tests on Windows in this code:

        let url_str =
            url::Url::from_file_path(&self.full_path).expect("Only absolute path is supported");
        IriAbsoluteString::try_from(format!("{url_str}")).expect("Failed to convert file path URI")
    }

• Could we support this using iri-string instead?
• Could we support this by some built-in Rust function that can turn a path into forward slashes?